Abstract: Based on enrichment characteristics and formation theory about low rank coal bed methane(LCBM)at home and abroad,national LCBM genetic types and formation models have been studied.The results show that genetic types of LCBM include thermogenic methane,biogenic methane and mixed methane.The characteristics of low rank coal reservoir include shallow bury,low contents,large thickness,high permeability and transformed easily,coexisting with other oil gas.Based on the previous research results of formation models dividing through lithology,structure conditions,locations and hydrogeololgy conditions,synthesize dynamic formation model has been proposed in this paper,including material base of favorable sedimental environment,migration pressure difference of constructs,methane supply and preserve of hydrogeololgy conditions,discussing new thought of selecting area of LCBM.Taking Yilan coal-bearing basin for an example,combined previous research results and geological conditions,reservoir forming and accumulation model of LCBM in China is proposed,which is advantage coal faces rich water area accumulation model in slope with coupling between primary and secondary origin.